announced the availability of the PCI Express Base 2.0 specification on 15 January 2007.[5] PCIe 2.0 doubles the bus standard's bandwidth from 2.5 Gbit/s to 5 Gbit/s, meaning a x32 connector can transfer data at up to 16 GB/s in each direction.

PCIe 2.0 is backward and forward compatible with PCIe v1.x. Graphic cards and motherboards designed for v2.0 will be able to work with v1.1 and v1.0, and vice versa. In some rare cases it is possible that a PCI-E 2.0 card will not work correctly on a PCI-E 1.0a slot. This is only LIMITED to CERTAIN video cards.

The PCI-SIG also said PCIe 2.0 also features improvements to the point-to-point data transfer protocol and its software architecture.[6]

In June 2007 Intel released the specification of the P35 chipset which does not support PCIe 2.0 only PCIe 1.1.[7] Some people may be confused by the P35 block diagram[8] which states the Intel P35 has a PCIe x16 graphics link (8 GB/s) and 6 PCIe x1 links (500 MB/s each), for simple verification one can view the P965 block diagram which shows the same number of lanes and bandwidth but was released before PCIe 2.0 was finalized. Intel's first PCIe 2.0 capable chipset is the X38 and boards are already shipping from various vendors (Abit, Asus, Gigabyte) as of October 21, 2007.[9] AMD started supporting PCIe 2.0 with its RD700 chipset series. NVIDIA has revealed that the MCP72 will be their first PCIe 2.0 equipped chipset.[10]

Thanks michaewlewis

I'm still going to bye a motherboard with PCi-e 2.0 slots

at least that way I wont need to upgrade it, when most graphics cards become PCI-e 2.0